FAMILIARIZATION OF ELECTRICAL DISTRIBUTION LINE EQUIPMENT

GENERAL DEFINITION:
TRANSFORMER IS A DEVICE THAT TRANSFERS ELECTRICAL ENERGY FROM ONE ELECTRIC CIRCUIT TO ANOTHER WITHOUT A CHANGE IN FREQUENCY, DOES SO BY THE PRINCIPLE OF ELECTROMAGNETIC INDUCTION AND HAS ELECTRIC CIRCUITS THAT ARE LINKED BY A COMMON MAGNETIC CIRCUIT.

POWER TRANSFORMER
• BY TYPE (SUBSTATION POWER TRANSFORMER): – STEP UP – STEP DOWN

* THE POWER TRANSFORMER IS CONSIDERED AS THE “HEART” OF THE TRANSMISSION AND DISTRIBUTION SYSTEM

POWER CIRCUIT BREAKERS

POWER CIRCUIT BREAKER
DEFINITION: AN ELECTRICAL DEVICE CAPABLE OF:
1. CARRYING NORMAL LOAD CURRENT TO WHICH IT IS DESIGNED 2. MAKING AND BREAKING NORMAL LOAD CURRENT (CAPABLE OF MULTIPLE INTERRUPTION OF NORMAL LOAD CURRENT) 3. INTERRUPTING RATED FAULT CURRENT TO WHICH IT IS DESIGNED (CAPABLE OF MULTIPLE INTERRUPTION OF RATED FAULT CURRENT) 4. WITHSTANDING MOMENTARY FAULT CURRENT

MAIN FUNCTIONS/PURPOSES OF POWER CIRCUIT BREAKERS
1. INTERRUPT FAULT CURRENT AS QUICKLY AS POSSIBLE 2. ISOLATE AFFECTED CIRCUITS TO MINIMIZE DAMAGE TO OTHER EQUIPMENT 3. ENSURES CONTINUITY OF SERVICE

METHODS OF ARC DISTINGUISHING
1. OIL CIRCUIT BREAKER A. COOLING THE ARC BY PUMPING OIL INSIDE THE INTERRUPTER B. ABSORBS HEAT BROUGHT ABOUT BY THE ARC C. GOOD INSULATING MEDIUM WHICH PREVENTS RESTRIKING OF INTERRUPTED CURRENT 2. AIR CIRCUIT BREAKER A. BLOWING OF AIR TO THE ARC TOWARDS THE ARC CHUTES 3. GAS CIRCUIT BREAKER A. PUFFING SF6 GAS TO THE INTERRUPTER AND ABSORBING HEAT BROUGHT ABOUT BY THE ARC. B. HIGH DIELECTRIC STRENGTH OF SULFUR HEXAFLOURIDE (SF6) PREVENTS RESTRIKING OF INTERRUPTED CURRENT. 4. VACUUM CIRCUIT BREAKER A. AIR WHICH CONTRIBUTES TO ARC PRODUCTION IS ABSENT, THUS NO ARC IS PRODUCED DURING CURRENT INTERRUPTION.

Symbols Used in Transformer Voltage Ratings
NAME SYMBOL APPLICATION
To separate the voltage rating or ratings of separate windings.

EXAMPLES

Dash

/

7620 V

-

240/120 V

Slant or Slash

To separate voltage to be applied or to be obtained from the same winding. To designate separate voltages which can be obtained by reconnecting the coils of a winding in series or multiple combinations

Changing the DUAL VOLTAGE TAP is done by transferring the connection of the primary lead

Samples of DTs With Dual Voltage Tap
Changing the DUAL VOLTAGE TAP is done by transferring the connection of the outer end of the curved copper strip

Dual Voltage Taps

SECTIONALIZING EQUIPMENT

SECTIONALIZING
Sectionalizing is the proper application of isolating and overcurrent protective devices to: 1. Facilitate manual and automatic line switching 2. Limit power interruption to the smallest practical segment of the line

RATIONALE
The primary objective of sectionalizing is to minimize the extent and effect

of power interruption in a circuit through the proper application of isolating and protective line equipment.

SWITCH
• A device for making, breaking or changing the connection in an electric circuit • It should be able to carry the normal load current continuously • It should also be able to handle abnormal or short circuit currents for short periods

Disconnect Switch
• • Plain knife-blade switch Has no interrupter and is intended to be operated only when the circuit has been de-energized by some other means Applications: primary line switch (PLS), disconnect switch

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Air Break Switch
• A disconnecting switch equipped with an arcing horn Can be operated with the circuit energized but carrying only charging or magnetizing current The arcing horn helps extinguish the opening arc by extending it as the switch contacts open

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Load Break Switch
• A disconnecting switch equipped with an interrupter Can be operated when the circuit is energized and carrying normal load current Can also be closed against a fault

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Remote-Controlled Line Switch
• An LBS that can be
operated remotely through SCADA measure voltage, current and other circuit parameters advanced type of electronic control, an RCLS can function like a sectionalizer

• It has the capability to

• If provided with the more

FUSE
• An overcurrent protective device which is placed in series in a circuit and has an element that melts during the passage of an overcurrent through it and thus interrupts the circuit A fuse must be replaced after its operation

Fuse Link
• Used in protecting distribution transformers, line capacitor banks, and lateral taps Can be applied for fault currents up to 5,000 amperes and load below 4 MVA Easily opened and closed using a telescopic hot stick

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Power Fuse
• Used in protecting transformer vaults and primary-metered services in high fault areas • Can be applied for fault currents up to 28,000 amperes and loads up to 12 MVA

Type SM-5 Power Fuse
• Can be applied for fault currents up to 28,000 amperes and loads up to 12 MVA Uses a porcelain fuse holder Can be opened with a telescopic hot stick but must be closed using a hook stick from a basket truck

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Type SMD-20 Power Fuse
• Can be applied for fault currents up to 10,000 amperes and loads up to 8 MVA Uses a fiber fuse holder Can be opened and closed using a telescopic hot stick

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Current Limiting Fuse (CLF)
• Used in conjunction with a fuse link to protect distribution transformers in high fault areas as well as station service transformers • Has no time-current characteristic (TCC) and operates only at high fault current magnitudes • Has no external moving parts that could indicate its operation

DESCRIPTION
An Automatic Circuit Recloser is a selfcontained device with the necessary intelligence to sense an overcurrent condition, interrupt the current flow, and then after a predetermined time delay, recloses automatically to reenergize the line. If the fault is permanent, it locks open after a pre-set number of operations thus isolating the faulted portion from the main part of the system.

RECLOSER
• A self-contained device with the necessary intelligence to sense an overcurrent condition, interrupt the current flow, & then after a predetermined time delay, recloses automatically to reenergize the line. If the fault is permanent, it locks open after a pre-set number of operations thus isolating the faulted portion from the main part of the system.

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RECLOSER CLASSIFICATIONS
1. Phase
Single-phase or three-phase

2. Control
Hydraulic or electronic

3. Interrupters
Oil or Vacuum

4. Insulation
Oil , Air or Epoxy

SINGLE-PHASE RECLOSERS
• Used to protect single-phase lines such as single-phase laterals Can also be used on threephase circuits where the load is predominantly single-phase Examples are the Type D (15.5 kV) and DV (38 kV) Kyle Reclosers from Cooper Power Systems

TYPES OF CONTROL
1. Hydraulic Control
• • Built as an integral part of the recloser Overcurrent is sensed by a trip coil that is connected in series with the line. When the overcurrent flows through the coil, a plunger is drawn into the coil to trip open the recloser contacts. Timing and sequencing are accomplished by pumping oil through separate hydraulic chambers or ducts.

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TYPES OF CONTROL
2. Electronic Control
• More flexible, more easily customized and programmed, and many have advanced protection, metering, and automation functionality. Line current is sensed by special sensing current transformers in the recloser The electronic control is housed in a cabinet separate from the recloser and conveniently permits changes to operational settings.

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TYPES OF INTERRUPTING MEDIUM
1. Oil Interrupters
• Reclosers using oil for current interruption use the same oil for basic insulation. Some reclosers with hydraulic control also use the same oil for timing and counting functions.

OPERATING LEVERS & INDICATORS
1. Manual Operating Handle
• A yellow lever that is used to manually trip the recloser • For the Type DV recloser, this is also used to close the recloser. • For the Type KFME, WE, WVE & VWVE reclosers, this is used for manual tripping & to override the controls to keep the recloser open. This cannot be used to manually close the recloser but must be in the closed position (up) before the recloser contacts can be closed.

OPERATING LEVERS & INDICATORS
2. Contact Position Indicator
• A red flag that is also linked to the interrupter mechanism but independent of the yellow handle • It drops down from under the sleethood when the interrupter contacts are open.

THE KYLE TYPE DV RECLOSER
Operating Levers and Indicators
The DV Reclosers’ sleet hood, showing the manual operating handle, nonreclosing lever and contact position indicator. Also found under the sleet hood is the operations counter.

THE KYLE TYPE KFME RECLOSER
Operation
• Tripping & closing are initiated by signals from the electronic control • When currents in excess of the programmed minimum-trip value are detected in one or more phases, a signal from the control actuates a solenoid in the operating mechanism to trip the opening springs & open the interrupter contacts

Form 3A Control

Form 4C Control

THE KYLE TYPE KFME RECLOSER
Operation
• Closing energy and the force to charge the opening springs is supplied by a closing solenoid energized from the source side of the recloser

THE KYLE TYPE KFME RECLOSER
Operation
• Arc interruption takes place within the 3 sealed vacuum interrupters. • Oil is used for electrical insulation, but is not involved in arc interruption.

THE KYLE TYPE KFME RECLOSER
Electronic Control
• All operating parameters, like phase- and groundfault minimum trip levels, TCC selection & sequence of recloser operation are done via the electronic control • The Form 3A control is a solid-state electronic type while the Form 4C is a microprocessorbased control type

Form 3A Control

Form 4C Control

THE KYLE TYPE KFME RECLOSER

Typical Pole Installations

THE TYPE WE, WVE & VWVE RECLOSERS
Operation
• Closing energy & the force to required to charge the opening springs is supplied by a closing solenoid • Oil interrupters are used in WE & WVE. Vacuum interrupters are used in VWVE. • All are oil-insulated.

• A red flag labeled OPEN independent of the yellow handle • Drops down from under the sleethood when the interrupter contacts open

THE TYPE WE, WVE & VWVE RECLOSERS
Electronic Control
• As with the Type KFME recloser, all operating parameters for the Type WE, WVE & VWVE reclosers are provided by the electronic control • The controls used by MERALCO are the Form 3A solid-state electronic control & the Form 4C & Form 5 microprocessor-based controls

Form 3A Control Form 4C Control

Form 5 Control

Type WE & WVE Reclosers in service

FAULT INDICATOR
A device that indicates fault current flow Senses the magnetic field caused by the current flowing through the conductor Classified either as manual reset or automatic reset

SECTIONALIZERS

DESCRIPTION
A SECTIONALIZER is a self-contained electrical device that interrupts its load side after sensing the passage of a predetermined number of successive fault currents and the corresponding trippings of the backup device at its source side.

SECTIONALIZER
• A self-contained electrical device that interrupts its load side after sensing the passage of a predetermined number of successive fault currents & the corresponding trippings of the back-up device at its source side It opens during the open interval of the backup device

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OPERATION
• It opens during the open interval of the backup device • It does not interrupt fault current but can be closed into a faulted line • It can be used to interrupt normal load current • Once open, the sectionalizer will remain open until manually closed

The sectionalizer’s manual operating controls are located on the underside of the operator mechanism housing placed on one side of the sectionalizer’s tank.

AUTOMATIC VOLTAGE REGULATORS

Automatic Voltage Regulator
• A tap-changing autotransformer with the ability to continuously monitor its output voltage and automatically adjust itself by changing taps until the desired voltage is obtained. • It regulates line voltage from 10% raise (boost) to 10% lower (buck) in 32, approximately 5/8 steps.

Reasons for Installing AVRs
• To improve system voltage • To improve quality of service • To meet regulatory standards

MAJOR COMPONENTS OF AN AVR
Position Indicator
• Has a pointer mechanically connected to the tapchanging switch • Indicates the actual position of the tap-changer through the yellow pointer • Indicates the maximum & minimum positions attained during raise & lower operations through its drag hands. • Allows load bonus setting of the regulator

MAJOR COMPONENTS OF AN AVR
Series Arrester
• A bypass arrester connected across the series winding between the S & L bushings. • Limits the voltage developed across the series winding during lightning strikes, switching surges & line faults.

• A device for introducing a capacitive reactance in a circuit to counteract the effects of inductive reactance • It reduces the impedance of a circuit with a consequent reduction in the voltage drop and an improvement in the PF • By reducing the current required to supply a load, it decreases losses in a circuit

CAPACITOR

SAMPLE 200 KVAR, 13200 V, CAPACITOR UNIT

CAPACITOR BANKS

FACTORY-ASSEMBLED BLOCK WITH HORIZINTALLY MOUNTED CAPACITOR UNITS

ADVANTAGES OF HAVING A CAPACITOR BANK INSTALLATION
1. RAISE AND LOWER VOLTAGE WHEN NEEDED 2. RAISE VOLTAGE ON SOURCE SIDE 3. REDUCES LOSSES IN THE SYSTEM 4. REDUCES THERMAL LOADING 5. RAISES SYSTEM LOADING CAPABILITY

TYPES OF CAPACITOR BANKS
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Series Capacitor Bank

Connected in series with the line Used to compensate for the reactive voltage drop in the circuit Typically used in low-voltage, heavycurrent applications such as furnaces & welders, to compensate for the voltage drop in the conductors Connected in parallel with the load Used to correct the component of current caused by inductive loads Typically used for PF correction

GUIDELINES IN HANDLING CAPACITOR BANKS
1. Before placing a capacitor bank in service,
inspect individual units for bulged or cracked tanks. Proper care should be exercised in handling capacitor units to prevent damage to or denting of capacitor case.

2. Before working upon capacitor units, the

capacitor bank must be allowed to stand at least five (5) minutes after disconnecting from source of power, after which it shall be short-circuited and grounded before work is started.

ENERGIZING & DE-ENERGIZING LINE CAPACITOR BANKS
Always use the capacitor oil switch when energizing & de-energizing a capacitor bank. When the oil switch is inoperable, the following shall be observed:

1. Closing of FCOs shall be done only while the
line is de-energized

2. For line capacitor banks installed on 13.8kV

circuits & below, opening of FCOs shall be done with the use of load buster

3. For line capacitors installed on 34.5kV circuits,
opening of FCOs shall be done only when the line is de-energized

1. The oil switch is manually operated by means of the red handle under the sleet hood. Pulling down the handle will either open or close the switch depending upon its previous position. 2. A disc-type contact-position indicator shows the switch position.

Type TSC Oil Switch Operation
3. When the operating handle is pulled down, the manual reset lever is also pulled down. 4. When the operating handle is released, it automatically returns to its up position under the sleet hood. 5. The manual reset lever, however, must be returned to its up position before the motor circuit is armed & the switch is returned to remote electrical control.

Cooper’s Type NR Single-Phase Oil Switch

Nominal System Voltage Rated Maximum Voltage Rated Momentary Current Rated Making Current Capacitive Continuous Current

14.4 kV 15 kV 9000 A 9000 A 200 A

Manual Operation of the Type NR Oil Switch

The oil is manually opened & closed by operating the yellow handle under the sleet hood.